SAN'A, Yemen (AP) - An Al-Qaida terror cell was behind a mortar strike against the U.S. embassy in Yemen that missed its target but killed a security guard and wounded 13 students at a nearby school, an Interior Ministry official said Saturday. The official, speaking on customary condition of anonymity, said al- Qaida militant Hamza al-Dayan launched three mortars at the embassy Tuesday before fleeing the scene in a vehicle with three accomplices. The mortar shells crashed into the school in the downtown Sawan district of San'a, killing the security guard and wounding 13 schoolgirls, three grievously. On Thursday, the...